Contract Unbound
by SweetPetiteBun
Summary: Under Ciel's orders, Sebastian studies a Time Machine supposedly from the future. Turns out there is no Fantom company there, and villainous nobles are no longer needed for. Instead the job of the Phantomhives was taken over by...the Vongola. It would be best for Sebastian to quickly return to his time...but does he want to? (Originally written with World Travelling Chibitaku)
1. His Butler, Sent to the Future

**His Butler, Sent to the Future**

* * *

 **Prologue**

* * *

"…Alright. Bye."

The boy who had recently become a demon, Ciel Phantomhive, put down the phone. Ciel had just received notice from the Queen's messenger that they had found a strange machine—a machine which could supposedly send you to the future, as was written on the base of the strange contraption. The machine itself was also supposedly from the future-was the future generation of Great Britain trying to tell them something? Or was it just an accident? Or maybe the machine couldn't send you to the future at all...

However, there was no proof confirming any of those theories. The Queen's guard-dog wouldn't usually be involved in these matters, but if there was a machine which could send you to the future—there could surely be one which could send you to the past. That would be troubling for her Majesty if someone from the future tried to change history by killing her Majesty.

Which came to another troubling matter—if someone from the future allied themselves with the Queen's enemies—simply said, they were doomed.

Pinching the bridge of his nose, the child prodigy sighed and reached for his bell, ringing for Sebastian to come to his aid.

As usual, the demon butler arrived in the blink of an eye. "What is the problem, my lord?"

Ciel reached down, picked up the item and put it on his desk. He stood up and made a small cut at the top of the guitar sized package sitting on his table. Ciel unwrapped the machine and gestured for Sebastian to look at it.

"This is called the Time Machine—A machine which can supposedly send you to the future. You know how dangerous this could be in the wrong hands. I want you to find out whatever you can about this machine. I also want you to find out how to use this machine—it could be very useful for Her Majesty."

Sebastian bowed. "Yes, my lord..."

Ciel nodded. "You are dismissed."

Sebastian turned around and headed for the door, hand already grasping the doorknob when the machine moved. Hearing the noise, Sebastian looked behind himself and watched as the object launched itself at him, and swallowed him whole.

Ciel stared at the spot where Sebastian once was. "Oh well. At least he now knows what the future is like."

* * *

Sebastian wearily opened his eyes and found himself sitting in an unfamiliar place and slowly got up, his body on guard. As he did, he felt a searing pain coming from his left hand.

Fearing the inevitable, Sebastian made a quick motion and ripped his glove off.

There was nothing on his hand. He flipped over his hand looking at both sides, and noticing that there was no feeling of a new mark coming, his suspicions were confirmed.

The symbol of the contract was gone—which could only mean one thing.

The contract was broken.

Sebastian felt a small grin stretch across his face. The Young Master would certainly be trying to find him. And try to re-enact the contract. But this time, Sebastian wasn't so sure he would agree.

Ciel was a demon.

And it wasn't very fun to serve someone for eternity.

Of course, messing with time would have consequences...and he really should be figuring out how to get back to Young Master...but, well, Ciel could wait. He had all the time now since he was a demon.

Sebastian sighed to himself. He really shouldn't be here, he was probably breaking who knows how many laws right now for being here.

Oh well.

He was a demon, after all. He broke rules.

He snapped out of his thoughts and looked around. He was in front of a school with...Japanese (?)…words on it. He raked his hand though his hair, feeling a strand fall out of place, and gently shifted his hair back into place.

 _Ah...I'm rusty on my Japanese...why in the world would I be in Japan, and why in front of a school?_

Sebastian sighed again; walking around an unfamiliar place wasn't on his to-do list, to say the least. Then he heard footsteps followed by a voice,

"Herbivore, I'll bite you to death for trespassing on school grounds." He turned his head and saw a raven haired teen storming towards him.

* * *

 **Okay, so that was my first KHR (** **家庭教師 ヒットマン** **リボーン** **)** **and Kuroshitsuji** **（黒執事）** **Crossover. Hope you thought it was good, and hit that button down there and review!**


	2. His Butler, Meetings

**His Butler, Meetings**

* * *

 **Chapter One**

* * *

 _Sebastian sighed again; walking around an unfamiliar place wasn't on his to-do list, to say the least. Then he heard footsteps followed by a voice,_

 _"Herbivore, I'll bite you to death for trespassing on school grounds." He turned his head and saw a raven haired teen storming towards him._

Sebastian frowned. Herbivore was a term used to classify animals. He wasn't an animal. And was the teen supposed to be a vampire? Why else would he be biting people then? Or was it something Japanese people of this age did? Japanese people were strange…Swiftly turning and pinning the male to the wall of the school gate, Sebastian stared at the other, trying to find his true intentions. He saw nothing other than a thirst for entertainment.

"I am not a plant-eating animal." Releasing his grip, Sebastian jumped back, patting the imaginary dust off his clothing. "And I highly doubt you could even bite me, much less to death. Unless, you are a vampire. Even so, I still doubt you could."

The raven haired teen glared at him, and with something Sebastian recognized as anger, he snarled. "Carnivore then."

Sebastian smirked and almost chuckled at the stubborn child in front of him. People from the future were interesting. "Still wrong."

The male continued glaring at him.

Sebastian widened his smirk. "My name is not Herbivore, nor is it Carnivore. You may call me Sebastian. Remember that." With that, Sebastian walked off and seemingly disappeared.

Hibari glared at where the man—Sebastian, once stood. "Hn. Hibari Kyoya." Knowing that Sebastian was listening, Hibari continued. "I don't usually meet Carnivores…but change is good."

Sebastian, hidden in the shadows, smirked.

 _Indeed, Hibari Kyoya._

* * *

Sebastian aimlessly wandered around the school-which he came to know was called Namimori, according to what he could interpret of the sign. The young master would surely want to know what the future was like-and Sebastian was quite sure that saying the people of the future were vampires wouldn't be enough.

Looking up, Sebastian saw a rough outline of a heat source hidden in the trees-invisible to humans without heat-seeking machines, but Sebastian pretty much had one built into him. He did think it was a little strange that it was so small, but perhaps there were intelligent children in the future as well.

Someone was following him, eh?

How amusing.

He winked at the mystery person was following him and continued strolling around the school.

* * *

Reborn narrowed his eyes at the strange man who called himself Sebastian. First, he showed up in Namimori with no reason at all, managed to pin _Hibari-_ Hibari, the fearful cloud guardian of the Vongola family, self-proclaimed Carnivore Extraordinaire to a wall.

And also, the same man had just winked at him. He was being hidden by one of the latest edition of Mist disguises. And yet the strange man had found him. Ah, Verde would probably use this man as some kind of test subject once he learned of his existence...

* * *

Sebastian ran his hand through his hair. From what he could tell, today was either Sunday or Saturday, due to the fact that there were no students on school grounds. Or maybe school had ended, but that couldn't be right, according to the position of the sun.

"Carnivore!"

Sebastian lazily glanced behind himself. There was the teen he had met earlier-Hibari Kyoya, was it?

Bringing up his tonfas in a defensive stance, Hibari turned to Sebastian. "Fight me."

Sebastian raised an eyebrow at this and starting to pivot and walk away. "I apologize, but I must be..."

He was interrupted rather rudely when Hibari charged at him without warning, raising his tonfas. Sighing, Sebastian simply sidestepped the charging teen.

 _Really, how troublesome._

"It's not over yet."

Sebastian spun around to smirk at Hibari. "What?" He asked, feigning innocence.

To Sebastian's surprise, instead of attacking again, Hibari took out a purple box and lighted it with a...flame on his finger? The flame appeared to be coming from a ring-as soon as he inserted the flame into the box, smoke started surrounding the two. Was the box supposed to be some sort of dynamite? Or smoke bomb? But it smelt different...

To his mild amusement, when the smoke cleared, instead of the box exploding like a grenade, an animal Sebastian recognized as a hedgehog appeared.

 _Did people of the future use domestic pets as weapons? Do they throw them at their opponent?_

Sebastian made a mental note to research using pets as weapons.

* * *

In the beginning, Sebastian was in a rush to get back to the manor-he would be a disgrace to the Head Butler of Phantomhive name if he allowed himself to be late in preparing the Young Master's dinner...

But seeing the whining hedgehog in front of him which had just grown to a scientifically impossible size (that would've flattened Sebastian if he wasn't a demon), Sebastian knew that the Young Master would skin him alive if he didn't manage to get a sample of that DNA. This wasn't an accidental trip to the future anymore-this was business.

And he wouldn't be a Phantomhive butler if he couldn't get to the bottom of this animal-weapons-which-come-out-of-boxes-thing.

* * *

Sebastian picked up the scared hedgehog. "If you excuse me, I'll be collecting this..."

Moving impossibly fast for a human (at this Sebastian wondered if Hibari was really human or not, after all, he had an unnatural aura-he could be the love child of a reaper and human, that would explain the speed.) Hibari latched a pair of handcuffs onto Sebastian's hands.

Sebastian raised an eyebrow. "Do you really think that a pair of handcuffs can stop me?"

Hibari smirked up at Sebastian. "No. One won't." Sebastian watched as one became two, and two became three. "But maybe ten would. Or even twenty."

Sebastian actually grinned at this. Humans...really...were so pitiful. But for such stupid beings, sometimes, they were unbelievably smart.

"Do you really think that?"

Sebastian allowed himself a moment of pride as he watched the horror stricken expression of Hibari when he noticed the crack in his handcuffs. As if in slow motion, the handcuffs shattered, breaking into pieces that only a Demon Butler could put back together.

Picking up pieces of the handcuffs that were on the ground, Sebastian allowed Hibari to have the honour of looking at a demon's eyes.

"Then you are a fool."

* * *

Hibari widened his eyes just slightly. _Weird Carnivore...kamikorosu._

In the blink of an eye, Hibari had his tonfas out while retrieving the last of the pieces of the handcuffs back into the box to regenerate.

At this, Sebastian allowed himself a moment of surprise.

So this was what the future was like...Unnaturally fast humans, boxes contained animals and could repair the unrepairable...and most importantly, that strange purple glow that surrounded the box and Hibari.

And then Hibari charged once more, swiping at Sebastian's head, aiming to kill.

* * *

As expected, Sebastian simply dodged, Hibari's hit missed, however it managed to clip the back of Sebastian's tailcoat.

"Oh, and I really liked this new tux I got too." Sebastian mockingly taunted, while narrowly jumping away from Hibari who was striving to hit Sebastian just once, even if it was only a brush against the arm or leg.

Sebastian drew out his forks- they were rather dull, but it would be sharp enough to kill, and he only had a handful of these specific types of silverware which didn't bear the Phantomhive name, in case the people of the future could use it to find out who he was, and threw them at Hibari while launching himself into midair. Hibari blocked the forks with his tonfas and jumped up after Sebastian. They tried to hit each other, while quickly falling back to the ground.

Then the ground wavered and cracked, pieces flying up into the sky, other parts sinking downwards.

* * *

"My, my...what a waste of precious silverware."

Hibari, surrounded by a barricade of knives and forks, managed to send a glare at Sebastian.

"Now...Mr. Hibari, it would be much easier for both of us if you did not send such a nasty look towards me." Turning towards Hibari, Sebastian took out a single knife out of his suit pocket. "Now...Goodbye, Hibari Kyoya."

"Phantomhive."

Sebastian looked down at Hibari slightly shocked. "May you repeat that?"

"You work for the Phantomhives." Hibari repeated, holding up a single knife with Phantomhive neatly printed on it.

"Strange...I am quite sure I did not throw a single piece of silverware with the Phantomhive name engraved on it...I believe you can explain that, can't you, Mukuro?"

"Kufufu...You've gotten better, haven't you? It's been a long time since I've seen you..."

Reborn leaned closer to listen to the next piece of information. This could end up being very useful.

"In _hell._ "

* * *

 **Interesting things will happen, but no, this is not a Sebastian x Ciel story, well not really.**

 **Anyways, please review!**


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